Stylus for copy milling

ABSTRACT

A stylus for use in copy milling at different transfer ratios in different axes. The apparatus aspects of the invention comprises a sensing stylus having an elliptical cross section and/or an elliptical tip in which the elliptical section is generated as a semi-rotational or half of an ellipsoid wherein the dimensions of major and minor axes of such ellipse are derived as the product of the diameter of the tool multiplied by the inverse value of the transfer ratio in the respective axes of the tracing directions.

nited States Patent [1 1 Rossberger [451 Feb. 112, MM

[ STYLUS FOR COPY MILLING [75] Inventor: Franz Rossberger, Munich,

Germany [73] Assignee: Friedrich Deckel Aktiengesellschaft,

Mun r ny...

[22] Filed: Sept. 20, 1971 [21] Appl. No.: 181,764

[ Foreign Application Priority Data p lm fl h Germa y-,- --.-,2Q17 1 [52] US. Cl 90/62 R [51] Int. Cl. 1323c l/l6 [58] Field of Search 90/62 R; 13 R; 33/23 K;

82/14 R, 14 A; 51/100 R [56] References Cited UNITED STATES PATENTS Vertin 90/l3.8

816,700 4/1906 Barr 90/62 Primary Examiner-Gil Weidenfeld Attorney, Agent, or Firm-Woodhams, Blanchard & Flynn [57] TRACT A stylus for use in copy milling at different transfer ratios in difierent axes. The apparatus aspects of the invention comprises a sensing stylus having an elliptical cross section and/or an elliptical tip in which the elliptical section is generated as a semi-rotational or half of an ellipsoid wherein the dimensions of major and minor axes of such ellipse are derived as the product of the diameter of the tool multiplied by the inverse value of the transfer ratio in the respective axes of the tracing directions.

10 Claims, 7 Drawing Figures PATENTED 3.791 2559 saw 1 or 2 INVENTOR v FP4/1 Z MSSBZFGZE STYLUS FOR COPY MILLING The invention relates to a tracer pin for copying, particularly by copy milling, in which an original piece, a

model, a template or the like, is traced by means of the tracer pin and in which different transfer ratios can be chosen in different axes by adjusting the transfer element or elements and, as a rule, by also adjusting a further transfer element which is superposed to at least one of said transfer elements. This latter occurs, for example, during the expansion or reduction operations in so-called roller engraving by adjusting a pantograph and the gear transfer ratio of a roller drive.

Methods for copying with transfer ratios which vary in different directions serve to create two or threedimensional forms which are, compared with the original form or the original piece, expanded or reduced in at least one of their several dimensions. A situation for the use of such a method occurs, for example, in the manufacture of china the design of a soup plate or a long round meat plate is to be copied from a substantially circular flat dinner plate. Other cases will be ap parent in which a higher level of accuracy is required than in the above example.

In the case of copy milling at a transfer ratio which is equal in all axes, the dimensions of the tracer pin and the mill are chosen to be of equal ratios whereby said tracer pin has a circular cross section and a primarily semi-spherical tip.

It is known for copying, or more particularly for copy milling at transfer ratios which vary in different axes, to adjust the size of the tracer pin and the mill with respect to one another according to one of the transfer ratios. This method has the disadvantage that the pieces which are formed from the original form or piece correspond to one another only in the axis whose transfer ratio is the basis for the ratio of the size of the tracer pin to the size of the mill. On the other hand, the ratio of the dimensions in the other axes of the tracer pin and the mill which ratio is necessarily different from the transfer ratio in the first mentioned axis, and this results in distortions in the copied article.

Because of the disadvantages of a distortion and an inaccurate copying, this method can, in the case of transfer ratios which differ in two axes, be used only for line engraving. The disadvantages are in such case not very important because the line engraving works with tracer pins and mills of a pointed or conical design and the depth and also the width of the engraving is adjusted by the feeding the tool to the workpiece.

Even more limited is the use of the known method for copy milling at different transfer ratios in three axes. Here at best freely standing forms can be copied in which inaccuracies are dealt with by blending same into the general appearance.

Further, with known methods, it is not possible to provide a reproduction of original pieces, which reproduction is correct in size in the respective transfer ratios.

Thus, the basic purpose of the invention is to produce a tracing pin for copying, particularly for copy milling, in which an original piece, a model, a template or the like is traced by means of the tracer pin or stylus, and in which in various axes different transfer ratios can be chosen, through which there can be obtained a reproduction of the original piece, which reproduction is of correct size, according to the selected transfer ratios in the respective axes and which is characterized by minimum expense.

In the use of the tracing pin for copying, particularly for copy-milling, an original piece, a model, a template or the like, is traced by means of a stylus and in different axes different transfer ratios can be chosen by adjusting the transfer element or the respective transfer elements and, as a rule, a further transfer element which is superposed to at least one of said first mentioned transfer elements. The inventive attainment of the purpose consists in utilizing a tracer pin with an elliptical cross section and/or an elliptical tip in form of a semirotation ellipsoid in which the dimensions of the major and minor axes of the ellipse correspond to the product of the diameter of the tool multiplied with the inverse value of the transfer ratios in the respective axes of the tracing directions.

Through this product an operation is obtained as if the tool independent of its rotation would be dimensioned corresponding to the different ratios in the different axes. Thus for example at transfer ratios of l :2 in the x-axis and 1:4 in the y-axis of an elliptic cross section, the dimensions of which are in the major axis onehalf and in the minor axis one-fourth of the diameter of the stylus of circular cross section. Workpieces which are copied, by means of this method, from an original piece or the like at different transfer ratios in different axes have dimensions in each axis which correspond exactly to the transfer ratio associated therein. The inventive method permits a distortion-free and deviationfree reproduction of original pieces which reproduction is correct in size in the respective transfer ratios.

When a tracer pin is utilized with transfer ratios which are different in two axes as a rule the xand the yaxis which axes are positioned perpendicularly or approximately perpendicularly to the axis of the tracer pin, the tracer pin is provided according to the invention which has a cross section in form of an ellipse. The dimension of said ellipse corresponds in the major and the minor axes or the reversal thereof to the product of the diameter of the tool multiplied with the inverse value of the transfer ratio in the xor the y-axes.

When a tracer pin is utilized with transfer ratios which are different in two axes as a rule the xand the yaxes, which axes are positioned perpendicularly or approximately perpendicularly to the axis of the tracer pin, and a transfer ratio which equals this trans fer ratio in the axis as a rule the z-axis which is coincident, or approximately coincident, with the axis of the tracer pin, the tracer pin has, according to the invention, in addition to the feature described in the preceding paragraph, a tip in the form of a semirotation ellipsoid, the axis of rotation of which is positioned perpendicularly to the two axes with equal transfer ratio.

When a tracer pin is utilized with transfer ratios which are equal in two axes as a rule the xand the y-axis which are positioned perpendicularly or approximately perpendicularly to the axis of the stylus, and a transfer ratio which differs from said transfer ratios in the axis as a rule the z-axis which corresponds, or approximately corresponds, to, the axis of the tracer pin, the tracer pin according to the invention at a conventional circular surfacelike cross section of the shaft has a tip in form of a seimirotation ellipsoid, the axis of rotation of which is coaxial, or approximately so, to the axis of the tracer pin and the major axis of which during reduction or its minor axis during expansion is positioned on the axis of rotation.

It is to be understood that a duplicating machine or a copy mill is required in combination with the tracer pin or stylus. The technical and the economical expenditure for performing a duplicating method by utilizing the tracing pin described above are thus maintained very low.

Finally the invention also suggests that the tracer pin is provided on its periphery in the major or, if necessary, in the minor axis with a setting or adjusting means, like an arbor, a cam, a slot, plane surfaces, a mark or the like. Thus the tracer pin can be set and adjusted precisely in a simple and reliable manner in its axis.

The invention is illustrated in the drawings:

FIG. 1 is a schematized top view of a model with a tracer pin and, corresponding thereto, of a workpiece with a tool,

FIG. 2 is a schematized top view of a different model with a tracer pin and, corresponding thereto, ofa workpiece with a tool,

FIGS. 3 to illustrate the sections of different tracer pins effective to carry out the invention, each in one or two lateral views.

FIGS. 1 or 2 illustrate the inner contour 13, 14 of an original piece, here a template 11,12, and the already copied inner contour 23,24 of a workpiece 21,22. A tracer pin, or stylus, 31,32 and a tool 41,42 are connected by means of a symbolically illustrated transfer system 5 which consists of conventional transfer elements with transfer ratios which can be differently adjusted in different axes so that through the movement of the tracer pin 31,32 along the inner contour 13,14 of the template 11,12, at transfer ratios which differ in different axes, the movement of the tool 41,42, here a mill, is controlled in the workpiece for producing the inner contour 23,24. The path of movement of the tracer pin 31,32 is indicated with a dash-dotted line a" and the path of movement of the tool 41,42 with a dash-dotted line b." The tracer point 31,32 has a cross section in form of an ellipsoid, the dimensions n r and n of which in the x-axis and in the y-axis, the major or the minor axis or the reversal thereof, corresponds to the product of the diameter d of the tool 41,42 multiplied with the inverse value of the transfer ratio in FIG. 1 of 1:4 in the x-axis and 1:2 in the y-axis in FIG. 2 of 4:1 in the x-axis and 2:1 in the y-axis.

According to FIG. 3, the radial facing side a tracer pin 5 has a cross section Q in the form of an ellipse, the dimensions of which correspond in the xand in the yaxis to the product of the diameter ofa tool used multiplied with the inverse value of the chosen transfer ratio in the xor in the y-axis. Such a tracer pin is used for performing the duplicating method at transfer ratios which differ in two axes, here the xand the y-axis, which are positioned perpendicularly or approximately perpendicularly to the axis of the tracer pin. It is also effective for roughing, and in all cases in which a tool, as a mill, is used having its front face positioned perpendicularly to its axis.

According to FIGS. 4 and 5 the radial facing side of a tracer pin 6 or 7 has, aside from a construction like the tracer pin 5, a tip 61, 71 in form of a semirotation 6 to FIG. 4, in the yand the z-axis and according to FIG. 5 in the xand the z-axis. Tracer pins of this type are used for performing the duplicating method at transfer ratios which differ in two axes as a rule the xand the y-axis which are positioned perpendicularly or approximately perpendicularly to the axis of the tracer pin. Such tracer pins will also perform the duplicating method at a transfer ratio which equals one of said transfer ratios in the axis which corresponds to, or approximately corresponds to the axis of the tracer pin as a rule the z-axis.

According to FIGS. 6 and 7, the tracer pin 8,9 at a conventional circular-surfacelike cross section Q of the shaft has a tip 81 or 91 in form of a semirotation or half of an ellipsoid, the axis of rotation m of which is coaxial or approximately so to the major axis p of the tracer pin during reduction or to the minor axis q during expansion. Tracer pins of this construction must be used for performing the duplicating method at transfer ratios which are equal in two axes as a rule the xand the y-axis which are positioned perpendicularly or approximately perpendicularly to the axis of the tracer pin, and a transfer ratio which differs from said transfer ratios in the axis as a rule the z-axis which corresponds or is approximate to the axis of the tracer pin.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as fol lows:

l. A stylus for use in copy milling apparatus having a guide template engagable by said stylus, a milling tool of a first diameter and a transfer mechanism for conveying the movement of said stylus having direction components along at least two mutually perpendicular axes to said tool through differing transfer ratios existing between each axis of said two axes of movement, comprising:

means defining an elongated body having means defining a tip at one end; and

means on said elongated body defining an elliptical guide template engaging surface, the dimension of a major axis and a minor axis of said elliptical template engaging surface being equal to said first diameter of said tool multiplied by the inverse of the respective transfer ratio of said transfer mechanism between said stylus and said tool along each of said two axes of movement.

2. A stylus according to claim 1, wherein said template engaging surface means is the radial facing side of said stylus.

3. A stylus according to claim 1, wherein said template engaging surface means is said tip means.

4. A stylus according to claim 1, wherein said template engaging surface means is the radial facing side of said stylus and said tip means.

5. A stylus according to claim 1, wherein said template engaging surface means is said tip means; and

wherein said tip means is composed of at least half of an ellipsoid, said major axis of which is coaxial with the axis of said elongated body means.

6. A stylus according to claim 1, wherein said template engaging surface means is the radial facing side of said stylus; and

wherein said tip means is composed of a flat surface the plane of which is perpendicular to the longitudinal axis of said body.

cal template engaging surface means on said tip means is half of an ellipsoid.

9. A stylus according to claim 8, wherein said half of said ellipsoid is defined by a cutting plane containing said minor axis at the midpoint of said major axis.

10. A stylus according to claim 8, wherein said half of said ellipsoid is defined by a cutting plane containing said major axis at the midpoint of said minor axis. 

1. A stylus for use in copy milling apparatus having a guide template engagable by said stylus, a milling tool of a first diameter and a transfer mechanism for conveying the movement of said stylus having direction components along at least two mutually perpendicular axes to said tool through differing transfer ratios existing between each axis of said two axes of movement, comprising: means defining an elongated body having means defining a tip at one end; and means on said elongated body defining an elliptical guide template engaging surface, the dimension of a major axis and a minor axis of said elliptical template engaging surface being equal to said first diameter of said tool multiplied by the inverse of the respective transfer ratio of said transfer mechanism between said stylus and said tool along each of said two axes of movement.
 2. A stylus according to claim 1, wherein said template engaging surface means is the radial facing side of said stylus.
 3. A stylus according to claim 1, wherein said template engaging surface means is said tip means.
 4. A stylus according to claim 1, wherein said template engaging surface means is the radial facing side of said stylus and said tip means.
 5. A stylus according to claim 1, wherein said template engaging surface means is said tip means; and wherein said tip means is composed of at least half of an ellipsoid, said major axis of which is coaxial with the axis of said elongated body means.
 6. A stylus according to claim 1, wherein said template engaging surface means is the radial facing side of said stylus; and wherein said tip means is composed of a flat surface the plane of which is perpendicular to the longitudinal axis of said body.
 7. A stylus according to claim 1, wherein said elliptical template engaging surface means is both the radial facing side of said stylus and said tip means, said major and minor axes of said radial facing side being perpendicular to the longitudinal axis of said body, said major axis of said tip means being coincident with said major axis of said radial facing side and said minor axis of said tip means being coincident with said minor axis of said radial facing side.
 8. A stylus according to claim 7, wherein said elliptical template engaging surface means on said tip means is half of an ellipsoid.
 9. A stylus according to claim 8, wherein said half of said ellipsoid is defined by a cutting plane containing said minor axis at the midpoint of said major axis.
 10. A stylus according to claim 8, wherein said half of said ellipsoid is defined by a cutting plane containing said major axis at the midpoint of said minor axis. 